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.\" @(#)isblank.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/locale/isblank.3,v 1.19 2004/08/21 07:37:08 tjr Exp $
.\"
.Dd August 21, 2004
.Dt ISBLANK 3
.Os
.Sh NAME
.Nm isblank
.Nd space or tab character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isblank "int c"
.Sh DESCRIPTION
The
.Fn isblank
function tests for a space or tab character.
For any locale, this includes the following standard characters:
.Pp
.Bl -column \&`\et''___ \&``\et''___
.It "\&``\et''\t`` ''"
.El
.Pp
In the "C" locale,
.Fn isblank
successful test is limited to these characters only.
For single C
.Va char Ns s
locales (see
.Xr multibyte 3 ) ,
the value of the argument is
representable as an
.Li unsigned char
or the value of
.Dv EOF .
.Sh COMPATIBILITY
The
.Bx 4.4
extension of accepting arguments outside of the range of the
.Vt "unsigned char"
type in locales with large character sets is considered obsolete
and may not be supported in future releases.
The
.Fn iswblank
function should be used instead.
.Sh RETURN VALUES
The
.Fn isblank
function returns zero if the character tests false and
returns non-zero if the character tests true.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr isalnum_l 3 ,
.Xr iswblank 3 ,
.Xr multibyte 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isblank
function
conforms to
.St -isoC-99 .